The present invention relates to the use of nanoscale materials in a composition which is applied to the surfaces of drive elements in order to prevent fatigue damage thereon. More particularly, this application protects the surfaces of drive elements against the formation of micropitting (gray staining, surface fatigue) and trench formation. The occurrence of fatigue damage on these surfaces is prevented or reduced as a result.
In the case of drive elements, excessively high mechanical stresses result in two kinds of damage:    1) Scuffing and wear, in the case of which the damage proceeds from the surface of the contact faces.    2) Fatigue damage, which originates in the structure below the stressed faces and ultimately ends in excavations, for example pitting, micropitting, trench formation.
For reduction of wear and scuffing, there is a multitude of additives and solid lubricants which are well known and frequently used.
To prevent fatigue damage, only very few effective measures are known. One measure is to increase the lubrication film thickness.
Fatigue wear (pitting) arises through local overloading of the material by periodic compressive stress. The fatigue of the material becomes visible through micropitting (gray staining, surface fatigue) or trenches on the surface of the material. At first, fine cracks form in the metal lattice 20 to 40 μm below the surface, and these lead to material excavation. The small, microscopically visible excavations on the tooth flank, referred to as micropitting or gray staining, are recognizable as matt gray regions. In the case of gear systems, micropitting can be observed on tooth flanks virtually in all speed ranges. In roller bearings too, very shallow excavations occur in the form of micropitting on the raceway in the region of the sliding contact. These connections are described in detail in DE 10 2007 036 856 A1 and the literature cited therein.
To improve the viscosity properties, different additives are used in lubricants in order to avoid or at least minimize the abovementioned damage in roller bearings, cogs, gears and the like. In this context, the fatigue damage which is referred to as micropitting formation and trench formation is that which leads to the most serious material impairments through the cracks which arise.
To avoid this fatigue damage, the following measures can be taken:                lowering the contact forces,        suitable selection of lubricant,        adequate lubricant supply,        favorable positioning and configuration of the lubrication sites,        avoidance of unlubricated states.        
With regard to the avoidance of fatigue phenomena, various studies have been undertaken, some of which have been attempts to improve the lubricity of lubricants by addition of various additives. More particularly, additives with which the friction between the components can be reduced or which have an improved viscosity have been examined.
For instance, DE-A 1 644 934 describes organophosphates as additives in lubricants, which are added as antifatigue additives.
DE 10 2007 036 856 A1, which has already been cited above, discloses the addition of polymers having ester groups, which are used as antifatigue additives in lubricants.
US 2003/0092585 A1 discloses thiazoles as antipitting additives.
EP 1 642 957 A1 relates to the use of MoS2 and molybdenum dithiocarbamate, which are used as additives in urea greases for power trains.
The above-described additives known from the prior art, such as organophosphates and thiazoles, are thermally unstable, being organic substances. Furthermore, they can vaporize under the operating conditions or can, as conventional antiwear additives, react particularly with the metal surfaces, meaning that they react predominantly at the roughness tips which come into contact, since sufficient energy is available there for a chemical reaction with the metallic friction layer as a result of the flash temperatures which occur. They can therefore at best act in a minor role as antipitting additives. Solid lubricants such as molybdenum disulfide, in contrast, because of their density, have a tendency to settle out of oil formulations and can also be corrosive. Since the solid particles are used with particle sizes in the μm range, there is a significant influence on the flow characteristics and an increase in viscosity, and also a departure from newtonian flow characteristics. This behavior worsens the availability of the additive in the lubrication gap. SEM studies on the surfaces of the metallic friction partners show that these structures or depressions have with dimensions distinctly below 1 μm. These depressions are not accessible to the μm-size solid lubricant particles.